Flexure strength and color change of reused IPS Empress 2 / 대한치과보철학회지

Development of new ceramic and esthetic need of patient increased the use of ceramic restorations. The purpose of this study was to confirm the possibility of recycling for IPS Empress2 which has a lot of advantages in esthetics. 1st, 2nd and 3rd pressed disc-shaped(10x1.5mm) IPS Empress 2 specimens were made with IPS Empress ingot(shade 200, Ivoclar, Liechtenstein) and pressing furnace(IPS Empress EP 500, Ivoclar, Liechtenstein). Flexure strength was measured with universal testing machine(Zwick 145641, Zwick, Germany), and color change and staining resistance of specimens were evaluated with colorimeter (Model TC-6FX, Tokyo Denshoku Co., Japan). The followings were drawn from this study : 1. Flexure strength of the 1st, the 2nd, and the 3rd pressed specimens showed 236.78 MPa, 247.16MPa, and 220.72MPa, respectively. Flexure strength of the 2nd pressed specimens was higher than others, but there's no statistical difference between them. 2. The color difference between the 1st and the 2nd pressed specimens was 3.25, and that between the 1st and the 3rd pressed specimens was 3.63(P<0.05). 3. The color change after staining of the 1st, the 2nd, and the 3rd pressed specimens were 1.43, 2.64, and 1.45, respectively. In this study, reused IPS Empress 2 specimens showed insignificant change of flexure strength and stain resistance, but they showed some color change according to reuse. From this results, the limited possibility of reuse for IPS Empress 2 could be considered.

THE SHEAR BOND STRENGTH OF RESIN TEETH TO THE DENTURE BASE RESIN / 대한치과보철학회지

The bond failure of resin teeth to denture base resin is one of the failure in prosthodontic treatment. The purpose of this study was to evaluate the bond strength of artificial resin teeth to the denture base resins. Specimens were made with heat curing acrylic resins (Vertex Rs, Lucitone 199) and artificial resin teeth (Tiger, Trubyte biotone, Endura, Orthosit, Trubyte bioform IPN) and the bond strength were measured with testing machine (Zwick, Germany) and the mode of bond failure were observed. The results were as follows; 1. The bond strength of Vertex Rs to artificial resin teeth was the highest in Trubyte biotone, and It was the lowest in Tiger and Trubyte bioform IPN 2. The bond strength of Lucitone 199 to artificial resin teeth were higher in Orthosit and Trubyte bioform IPN than in Tiger and Trubyte biotone. 3. The bond strength of Trubyte biotone to Vertex Rs was higher than to Lucitone 199 and that of the Trubyte bioform IPN to Lucitone 199 was higher than to Vertex Rs. 4. Nearly all bond failures of specimens occured cohesively within the resin teeth.

PHYSICAL PROPERTIES OF THE REUSED IPS EMPRESS CERAMIC PART III. STUDY ON THE STAIN RESISTANCE / 대한치과보철학회지

The purpose of this study was to investigate the possibility on recycling of IPS Empress ceramic for the wide use of esthetically pleased IPS-Empress ceramic in clinical prosthodontic treatment. The specimens were made of first, second, and third pressed IPS Empress ceramic and were immersed in 0.05% methylene blue solution for 24hours. The amount of color change before and after stainning was measured with colorimeter(Model Tc-6Fx, Denshoku Co., Tokyo, Japan). The change of E in first pressed ceramic was 18.33 and those in second and third pressed ceramics were 19.33 and 19.93 respectively. Although there was statistical difference among them, the differences were minute and acceptable. From the results of this study, the possibility of recycling of IPS Empress ceramic could be suggested.